Bruce Korb <[EMAIL PROTECTED]> writes: > WRT strict aliasing, I've never seen any data that indicated that the > language change was compelling. Consequently, as best I can tell it > was a marginal optimization improvement. So, I doubt its value. > Still, it should have had compiler warnings in advance.
I've seen programs that doubled in speed when strict aliasing was turned on. You won't see this effect on an x86, since all current x86 implementations are out-of-order processors. You can think of an out-of-order processor as doing on-the-fly perfectly accurate alias analysis. For in-order processors with complex scheduling requirements, strict aliasing can make a dramatic difference in execution time, because it give the compiler considerable freedom to reorder loads and stores. Ian
